1. Field of the Invention
This invention is generally directed to moldable synthetic or plastic building materials of the type utilized for decorative facing, veneers, building facades, panels, decorative trim, planters and the like, and more particularly, to moldable building material composites formed of acrylic polymers in which natural cellulose fibers are blended in order to obtain an end product which is not only water resistant and therefore suitable for both interior and exterior uses, but also an end product which exhibits substantial structural integrity. The products molded from the composites of the present invention exhibit sufficient strength and rigidity to be self-supporting and securable to other substructural elements utilizing conventional fasteners including nails and screws. The formed products may have a variety of surface characteristics so as to simulate quarried stone including coral, natural travertine, limestone, dolomite, or fossil rock.
2. History of the Related Art
In an effort to create lightweight and durable building components which simulate natural building materials, such as stone, efforts have been made to utilize various plastic polymers and resins including acrylic polymers to form moldable panels, veneers, decorative trimming, and the like. One such composite material which can be molded to form such construction elements is Jemonite.TM., which is a formulated plaster resin composite which is glass fiber reinforced and is marketed by Forton BV, under license from Parnel Kraft-Benncroft Ltd. The composite plaster resin is moldable to form products having a variety of surface finish characteristics and is particularly suitable for interior uses but is also capable of exterior applications when the end product is coated or sealed. Jemonite.TM. is a water base thermoset acrylic including 50% polymer solid and 50% water. A modified glass fiber reinforced gypsum is blended with the acrylic, together with melamine resin solids and ammonium chloride as a hardening agent. The structural integrity or strength of units formed from the composite is provided by adding type "E" fiberglass roving and chopped strands to the composite prior to molding. In some instances, continuous strand and surface veil mats are used when hand laminating panels from the acrylic resin. It has been noted, however, that the end products such as veneers and decorative wall panels formed often exhibit brittleness which makes it difficult to mount them to substructures utilizing conventional tools such as air driven nails or screws. In addition, the use of the glass fiber within the molded composite produces environmental drawbacks not only during the molding but when handled during construction. Due to the brittleness of the Jemonite.TM. material, it has not been possible to form large sheets of durable veneers without the likelihood of cracks being produced when the sheets are impacted by fasteners.